If $7a + 4b = -10$ and $4x + 6y = -7$, what is $-49a - 28b - 8x - 12y$ ?
Answer: $= -49a - 28b - 8x - 12y$ $= (-7) \cdot (7a + 4b) + (-2) \cdot (4x + 6y)$ $= (-7) \cdot (-10) + (-2) \cdot (-7)$ $= 70 + 14$ $= 84$